Fluid proximity sensor and drive mechanism to control distance of an object from the sensor

ABSTRACT

A unipressure fluid logic control and power supply device which utilizes a single air pressure source for sensing and indicating the proximity or gap between a sensor and a driven element. The same supply means provides power to an air motor which drives the driven member and maintains it in a desired position in relation to the proximity sensor. The sensing device includes a fluid oscillator adapted to drive the piston-type air motor and an air inhibitor which prevents the oscillator from operating whenever a sensed fluid signal indicates the proximity or position of the driven member is as desired.

United States Patent Karl A. Brandenberg Hayward, Calif. 761,238

Sept. 20, 1968 May 25, 1971 The Aro Corporation Bryan, Ohio InventorApplv No. Filed Patented Assignee FLUID PROXIMITY SENSOR AND DRIVEMECHANISM TO CONTROL DISTANCE OF AN References Cited UNITED STATESPATENTS 1l/l966 l/l967 9/1967 7/1968 12/1968 12/1968 Mowbroy PrimaryExaminerPaul E. Maslousky Attorney-Bair, Freeman and Molinare ABSTRACT:A unipressure fluid logic control and power supply device which utilizesa single air pressure source for sensing and indicating the proximity orgap between a sensor and a driven element. The same supply meansprovides power to an air motor which drives the driven member andmaintains it in a' desired position in relation to the proximity sensor.The sensing device includes a fluid oscillator adapted to drive thepiston-type air motor and an air inhibitor which prevents the oscillatorfrom operating whenever a sensed fluid signal indicates the proximity orposition of the driven member is as desired.

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BACKGROUND OF TH E INVENTION This invention relates to a fluid controldevice and more particularly to a unipressure fluid logic control andpower supply device adapted to sense a physical parameter and drive afluid motor in logical response to the sensed parameter.

The use of fluidic sensing devices to provide control signals forvarious fluid driven mechanical apparatus is well known. Normally suchfluid flow signals are provided through the operation of heavy dutyvalving elements having movable seats and seals operable in the pressureranges for pneumatic tools and the like of more than 50 p.s.i.g. Thesensitivity of such pneumatic sensing devices is limited.

To increase sensitivity, pure fluidic devices are often utilized.However, purefluidic devices operate best at low pressure, e.g. lessthan p.s.i.g. Thus, an interface must usually be provided between thelow-pressure signals of the pure fluidic devices and the output signalsto the machine which the fluidic control system is adapted to control.For example the interface mechanism may be a fluid actuated electricsignal. The electric signal in turn, will provide a signal to cause amechanical change in the configuration of the mechanical apparatus. Thistype of construction requires additional parts and results in additionalpossibilities of failure.

It is thus desirable, for many application, to provide a device which isadapted to control and drive an apparatus utilizing the same fluidpressure source. It is also desirable to maintain a high degree ofcontrol sensitivity for the apparatus. Obviously higher pressures wouldresult in a loss of sensitivity whereas lower pressures would result ina loss of fluid driving power. In pneumatic devices, control and drivingpressure in the range of 5 to 25 p.s.i.g. should provide sufficientcontrol sensitivity yet simultaneously supply sufficient fluid pressureto drive the apparatus. It is with these problems and considerationsthat the present invention was conceived.

SUMMARY OF THE INVENTION In a principal aspect, the present inventioncomprises a fluid controlled and driven motor which becomes operativewhen-' ever actuated by a fluid input signal in response to fluidcontrol means. The fluid input signal to the motor and the fluidpressure at which the fluid control means operate is substantially thesame. The fluid control means includes means for sensing a physicalparameter and means for logically responding to the sensed parameter toprovide an output signal which operates to drive the fluid motor means.

It is thus an object of the present invention to provide fluidcontrolled and operated motor means wherein the fluid control and thefluid driven motor operate at substantially the same pressure.

It is a further object of the present invention to provide fluidcontrolled and operated motor means which eliminates the necessity forinterfacing between the control section of the device and the motorsection of the device.

Still another object of the present invention is to provide fluidcontrolled and operated motor meanswhich can be FIGS. 3 through 8 areopposite end views of the com- I ponents of the fluid logic controlsystem for the fluid motor taken substantially along the lines 3-3, 4-4,5-5, 6-6, 7-7 and 8-8 of FIG. 2; and

FIG. 9 is a cross-sectional view of a proximity sensor nozzle used inthe control means.

DETAILEDIDESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates, ina diagrammatic view, the fluid circuitry of the control means for thecontrolled fluid motor of the present invention. An external fluidpressure supply is provided through a supply conduit 10. The nominaloperating pressure of the system is IQ p.s.i.g. with the range beingfrom 5 to 25 p.s.i.g. The supply conduit 10 is connected to a fluidinhibitor l2 and an oscillator 14 which comprise the control means ofthe invention. Thus, the control means (i.e. the inhibitor 12 and theoscillator 14) and the fluid motor comprising the device both have theirorigin of fluid flow at the supply conduit 10.

A proximity sensor 16 is connected to the inhibitor 12 and a fluid motordrive conduit 18 is connected from the oscillator 14 to a fluid drivemotor 20. As shown in FIG. 1, the sensor 16 senses a gap between thesensor 16 and an object 22 such as a stack of papers and provides asignal to the inhibitor 12. The inhibitor 12, in turn, provides a signalthrough a conduit 24 to the oscillator 14. If an appropriate gap is notsensed by the economically manufactured and easily adapted for numerousBRIEF DESCRIPTION OF THE DRAWINGS In the detailed description whichfollows, reference will be made to the drawings comprised of thefollowing F IGS.:

FIG. I is a diagrammatic circuit diagram of the combined motor andcontrol means of the invention;

FIG. 2 is a partial cross-sectional view of the motor and control systemof the invention;

sensor 16, then a fluid output through conduit 18 from oscillator 14causes the reciprocating piston-type, air motor 20 to reciprocate anddrive the object 22 to an appropriate distance or gap from sensor 16.

A piston rod 26 is thus cased to reciprocate in response to operation ofthe motor 20, thereby driving an endless belt 28 clockwise about pulleys29 and 30 and causing an attached paper carrier 22 to rise toward thesensor 16. When the papers on'carrier 22 are an appropriate distancefrom sensor 16, the signal through conduit 24 from inhibitor 12 tooscillator 14 causes fluid output from oscillator 14 to cease.Consequently, carrier 22 remains in a fixed position until sensor 16again senses an inappropriate gap.

Construction: of the air motor 20 is more completely illustrated in FIG.2. The motor 20 includes a body or cylinder housing 32 having a piston34 slidably mounted therein. The piston rod 26 is attached to the piston34 and extends through the end of the body 32 against a bearing 36 toinsure that the rod 26 is in smooth sealing engagement with the body 32.The rod 26 is held in communication with the piston 34 by means ofa nut42 which is threadedly attached to the inner end to the rod 26 thatpasses through an opening in the head of the piston 34. A spring 38 isslidably fitted over the rod 26 between the piston 34 and a washer 40 onthe inside of the body 32L The spring 38 acts to bias the piston 34against fluid pressure input from conduit 18 to the air motor.

A base 44 cooperates with the body 32 to provide a cylinder chamberagainst the piston 34. The base 44 is held in sealing engagement withthe body 32 by fastening means (not shown) through openings 45 in FIGS.7 and 8. A gasket 46 and U-cup 48 insure a tight seal between the base44 and body 32.

The base 44, a valve plate 50, a cover 52, and first and second flexiblemembranes 54 and 56 cooperate to provide the logic sensing and controlmeans on the inhibitor l2and oscillator 14 depicted in FIG. 1. The planviews of the base 44 and the valve plate 50 and the cover 52 areillustrated in FIGS. 3- through 8. The portions of the logic circuitnumbered in FIG. 1 are correspondingly numbered in FIGS. 2 through 8.Thus, in FIGS. 2 and 3, an opening 10 in cover plate 52corresponds tothe conduit 10 in FIG. 1. A second opening 60 corresponds to the conduit60 from the sensor 16 in FIG. 1.

Referring now to FIGS. 1, 3-8, the inhibitor includes a first diaphragmvalve or element 62 and a second diaphragm valve 64. These vales 62 and64 each have an inlet 66 and 67, respectively, an outlet 68 and 69,respectively, leading to the atmosphere through openings 70 and 71,respectively, and a control inlet 72.and 73, respectively.

The control inlet 72 is connected through a restrictor 65 with thesupply conduit and the sensor conduit 60. Inlet 72 is adapted to receivesignals from the sensor 16 which results from a change in the gapbetween sensor 16 and object 22. lnlet 66 is connected with supplyconduit 10 through a restrictor 74. Outlet 68 connects with controlinlet 73 and with the atmosphere through a restrictor 75 positioneddownstream from the connection of outlet 68 with control inlet 73. Asset forth before, the inhibitor 12 and oscillator 14 are connected byway of the conduit 24.

The oscillator 14 likewise includes a first diaphragm valve or element76 and a second diaphragm valve 78. In addition, the oscillator 14includes an accumulator chamber 80 having an inlet conduit 82 and anoutlet conduit 84. The inlet conduit 82 is connected through a variablerestrictor 85 to the control conduit 24 and also a supply conduit 87.The supply conduit 87 is connected with the main supply conduit 10through a restrictor 88.

The first valve 76 and second valve 78 are arranged and constructed inthe same manner as the valves 62 and 64 in the inhibitor 12 describedabove. Namely, the valves 76 and 78 each includes an inlet conduit 89and 90, respectively, which connects with an outlet conduit 91 and 92,-respectively. The outlet conduit 84 of the chamber 80 serves as thecontrol inlet for the first diaphragm valve 76. The outlet conduit 91 ofthe first diaphragm 76 is connected to the control inlet conduit 95 ofthe second diaphragm valve 78. A restrictor 96 is positioned downstreamfrom the connection of the control inlet 95 with the outlet conduit 91.The supply conduit 10 is connected through the restrictor 88 to theinlet conduit 90 of the second valve 78 and also connects by way of theoutlet conduit 18 to the motor 20.

All of the diaphragm valves 62, 64, 76 and 78 includes flexiblediaphragms 97 through 100 respectively in FIG. 1 which respond to fluidpressures through the respective control inlets and supply inlets. Ofcourse, the diaphragms 97-100 diagrammatically represented in FIG. 1correspond to a portion of the membranes 54 or 56 in FIG. 2 which arewedged between the cover plate 52 and valve plate 50, and valve plate 50and baseplate 44, respectively.

For example, membrane 56 between cover plate 52 and valve plate 50provides diaphragms 98 and 99 for valves 64 and 76 respectively.Depending upon the pressure acting upon the diaphragms 98 and 99 throughthe conduits on opposite sides of the diaphragms 98 and 99, thediaphragms 98 and 99 will be biased toward or away from ridges or seats106 and 107 respectively.

The switching pressure of the diaphragm valves is therefore dependentupon the area of the diaphragm surface subject to pressure from conduitson opposite sides of the diaphragm. For example, diaphragm 99 will notflex to allow opening of valve 76 until the product of the supplypressure and the area of the inlet conduit 89 is equal to orgreater'than the product of the control pressure through conduit 84 andthe area of the upper face of the diaphragm 99 as shown in FIG. 1. Theremaining valves 62, 64 and 78 are similarly constructed and operative.Thus, switch pressures and response characteristics of the completedevice may be controlled by controlling the dimensions and constructionof the diaphragm valves, especially the ratio of the areas of theflexible membrane subjected to pressure.

Referring now to FIG. 9, there is shown a cross-sectional view of theproximity sensor 16 used in conjunction with the invention. Fluid passesthrough the sensor 16 in the direction indicated by the arrow. An outletorifice 102 in the sensor 16 is formed by the intersection of an outsideplanar wall 103 and cylindrical walls of a passage 104 concentric abouta centerline axis 105. The edge of the orifice 102 formed by thejunction of the plane 103 and the sidewalls of the passage 104 is sharp,not rounded.

The operation of the device can be understood by reference again toFIG. 1. Operationvof the inhibitor stage 12 and sensor 16 is firstdescribed. Proximity is sensed by a fluid jet, such as an air jet,eminating from the orifice 102 of the sensor 16.

With close proximity, air pressure in the line 60 is high. Thiscausesthe diaphragm 97 and valve 62 to close and thereby permits the diaphragm98 and vale' 64 to open, pressure in the valve element 64 being relievedthrough the restrictor 75. Thus, no pressure can build up in inlet 67 ofvalve 64 since fluid flow passes through outlet conduit 69 and throughthe opening 71 to the atmosphere. Consequently, no signal impulse isgenerated in conduit 24 which will activate the oscillator 14.

With an increased gap between the sensor 16 and the object 22, thepressure in conduit 60 decreases causing the valve 62 to open and air toflow through restrictors 74 and 75. This results in an increasedpressure through control inlet 73. This, in turn, closes the valve 64.For this reason, pressure from the pressure conduit 87 can no longer bediverted through the conduit 24 to the inhibitor stage but must bediverted into the oscillator stage 14, making the oscillator 14operative. v

Proximity hyteresis can be adapted to requirements and is determined byrelations of restrictor 65 to the orifice 102, the restrictor 74 and 75,and cavity to seat diameter of valve 62.

Referring now to the operation of the oscillator 14, when valve 64 ofthe inhibitor stage 12 is closed, air flows through the meteringrestrictor 85 into the accumulator chamber 80 gradually building linepressure in conduit 84. After a time interval, dependent upon the volumeof chamber 80 and the construction of restrictor 84, equilibrium isreached on both sides of diaphragm 99 in valve 76. Valve 76 then closes.Pressure in outlet conduit 91 then discharges through atmosphericopening 93 causing valve 78 to open.

When valve 78 opens, pressure drops in supply line conduit 90 to element78 causing air to exhaust from the cylinder of the motor 20 through theconduit 18 and ultimately out at- 1 mospheric. vent or opening 94. Also,since pressure in conduit 90 drops, air flows from the chamber 80through the conduit 82, variable restrictor 85 and conduit 87 at ametered rate.

This causes gradual pressure drop in conduit 84 and eventually causeselement 76 to open.

Air now enters through restrictor 86 causing element 78 to close. Airthrough the supply restrictor 88 can then no longer pass to theatmosphere and pressure builds up on conduit 18 to drive the piston 34of the motor 20 against the biasing force of the spring 38. Air alsoreenters conduit 87, passes through the variable restrictor 85 andultimately into the chamber repeating the above-described oscillationoperation. This process continues until the belt 28 is drivensufficiently far enough in a clockwise sense so that the inhibitor 12senses a suitable proximity of the sensor 16 from object 22 thus causingvalve 64 to open and oscillator 14 to become inoperative. Note thatpiston rod 26 cooperates with the belt 28 as a ratchet mechanism todrive the belt 28 in a clockwise sense.

The oscillator 14 and inhibitor 12 can be built as separate units toserve independent applications such as proximity sensing for theinhibitor 12 or time based automatic cycling for the oscillator 14. Forexample, an inhibitor 12 could be used for proximity sensing and couldbe coupled with a NOT gate to provide an outlet which would drive arotary-type air motor. Such a construction would accomplish a resultsimilar to that described for the piston-type motor, oscillator andinhibitor combination described above and claimed hereinafter.

' lclaim:

l. Fluid driven motor means with fluid operated control means operativesimultaneously at substantially the same fluid pressure comprising, incombination:

fluid driven motor means; and

fluid pressure sensing means for sensing a measurable physical parameterand providing a logically responsive fluid output signal indicative ofsaid physical parameter, said fluid pressure sensing means including;

a pressure supply,

pressure input signal means indicative of the measurable physicalparameter,

first and second diaphragm valve means, each of said valve meansincluding a fluid flow inlet connected to signal means includes aproximity sensor for detecting a gap between said signal means and anobject, and proximity sensor including an orifice for fluid discharge.

eludes first restrictor means at said inlet to said first valve meansand a second restrictor means at said outlet of said first valve meansto the atmosphere.

said pressure supply, a fluid flow outlet connected to the atmosphere,and a control inlet, said input signal means being connected to saidcontrol inlet of said first valve means, said fluid flow outlet of saidfirst valve means also being connected with the control inlet of 5 saidsecond valve means such that an input signal closes the fluid flow pathfrom said inlet to said outlet of said first valve means and therebyopens the fluid flow path from said inlet to said outlet of said secondvalve means, said logically responsive output signal being therebyassociated with the fluid flow path of said second valve means, andfluid oscillator means for receiving said logically responsive outputsignal from said fluid pressure sensing means and responsive to saidoutput signal by providing an oscillatingfluid output driving signal tosaid motor means until said logically responsive output signalterminates. 2. The combination of claim I wherein said pressure input 3.The combination of claim I wherein said combination in- 4. Thecombination of claim 1 wherein said motor means includes a pistonresponsive to fluid flow output from said oscillator means, said pistonoperative to drive a piston rod which in turn changes said measurableparameter to a substantially preselected value sensed by said sensingmeans.

5. The combination of claim 1 including restrictor means in said supplyto said sensing means.

6. The combination of claim 1 wherein said motor means '35 operatesmeans to alter said measured parameter so that said logically responsiveoutput of said fluid pressure sensing means is terminated.

7. Fluid driven motor means with fluid operated control means operativesimultaneously at substantiallythe same fluid pressure comprising, incombination:

' fluid driven motor means; t

fluid pressure sensing means for sensing a measurable physical parameterand providing a logically responsive fluid output signal indicative ofsaid physical parameter; and

fluid oscillator means for receiving said output signal from said fluidsensing means and responsive to said output signal by providing anoscillating fluid output driving signal to said motor means until saidlogically responsive output signal terminates, said oscillator meansincluding;

an accumulator chamber having aninlet and an outlet,

a first diaphragm valve means 'and a second diaphragm valve means, eachof said valve means having a fluid flow inlet connected to a pressuresupply, a fluid flow outlet connected to the atmosphere and a controlinlet,

said accumulator chamber adapted to accumulate fluid in said accumulatorresulting from said logically responsive fluid output signal of saidfluid pressuresensing means to thereby provide an accumulator outletsignal to said control inlet of said first valve means following a timeinterval to fill said chamber, said chamber outlet signal operative toclose said first valve means and restrict fluid flow from said firstvalve means inlet through said first valve means outlet thereby torestrict a signal from said first valve means outlet to said controlinlet of said second valve means, thereby to open said flow path fromsaid second valve means inlet to said second valve means outlet, and

said second valve means inlet being also connected to said fluid motormeans and providing an exhaust-to said motor means when said fluid flowpath through said second valve means inlet and outlet to the atmosphereis open, said chamber inlet also being connected to said inlet of saidsecond valve means through restrictor means thereby to exhaust saidchamber simultaneously with the exhaustion of said motor means such thatupon exhaustion of said chamber, said first valve means opens and saidsecond valve means closes thereby to provide said motor with fluid untilsaid accumulator chamber again accumulates fluid causing the system tooscillate. 8. The combination of claim 7 wherein said restrictor meansis variable. i

9. The combination of claim 7 wherein said'combination in-.

cludes second restrictor means at said inlet to said first valve meansand third restrictor means at said outlet of said first valve means tothe atmosphere.

10. The combination of claim 7 whereinsaid motor means includes a pistonresponsive totfluid flow output from said oscillator means, said pistonoperative to drive a piston rod which in turn operates means to' changesaid measurable parameter to a substantially preselected value sensed bysaid sensing means.

1]. The combination of claim 7 including restrictor means in said supplyto said oscillator means.

12. The combination of claim 7 wherein said motor means operates meansto alter said measured parameter so that said logically responsiveoutput of said fluid pressure sensing means is terminated.

1. Fluid driven motor means with fluid operated control means operativesimultaneously at substantially the same fluid pressure comprising, incombination: fluid driven motor means; and fluid pressure sensing meansfor sensing a measurable physical parameter and providing a logicallyresponsive fluid output signal indicative of said physical parameter,said fluid pressure sensing means including; a pressure supply, pressureinput signal means indicative of the measurable physical parameter,first and second diaphragm valve means, each of said valve meansincluding a fluid flow inlet connected to said pressure supply, a fluidflow outlet connected to the atmosphere, and a control inlet, said inputsignal means being connected to said control inlet of said first valvemeans, said fluid flow outlet of said first valve means also beingconnected with the control inlet of said second valve means such that aninput signal closes the fluid flow path from said inlet to said outletof said first valve means and thereby opens the fluid flow path fromsaid inlet to said outlet of said second valve means, said logicallyresponsive output signal being thereby associated with the fluid flowpath of said second valve means, and fluid oscillator means forreceiving said logically responsive output signal from said fluidpressure sensing means and responsive to said output signal by providingan oscillating fluid output driving signal to said motor means untilsaid logically responsive output signal terminates.
 2. The combinationof claim 1 wherein said pressure input signal means includes a proximitysensor for detecting a gap between said signal means and an object, andproximity sensor including an orifice for fluid discharge.
 3. Thecombination of claim 1 wherein said combination includes firstrestrictor means at said inlet to said first valve means and a secondrestrictor means at said outlet of said first valve means to theatmosphere.
 4. The combination of claim 1 wherein said motor meansincludes a piston responsive to fluid flow output from said oscillatormeans, said piston operative to drive a piston rod which in turn changessaid measurable parameter to a substantially preselected value sensed bysaid sensing means.
 5. The combination of claim 1 including restrictormeans in said supply to said sensing means.
 6. The combination of claim1 wherein said motor means operates means to alter said measuredparameter so that said logically responsive output of said fluidpressure sensing means is terminated.
 7. Fluid driven motor means withfluid operated control means operative simultaneously at substantiallythe same fluid pressure comprising, in combination: fluid driven motormeans; fluid pressure sensing means for sEnsing a measurable physicalparameter and providing a logically responsive fluid output signalindicative of said physical parameter; and fluid oscillator means forreceiving said output signal from said fluid sensing means andresponsive to said output signal by providing an oscillating fluidoutput driving signal to said motor means until said logicallyresponsive output signal terminates, said oscillator means including; anaccumulator chamber having an inlet and an outlet, a first diaphragmvalve means and a second diaphragm valve means, each of said valve meanshaving a fluid flow inlet connected to a pressure supply, a fluid flowoutlet connected to the atmosphere and a control inlet, said accumulatorchamber adapted to accumulate fluid in said accumulator resulting fromsaid logically responsive fluid output signal of said fluid pressuresensing means to thereby provide an accumulator outlet signal to saidcontrol inlet of said first valve means following a time interval tofill said chamber, said chamber outlet signal operative to close saidfirst valve means and restrict fluid flow from said first valve meansinlet through said first valve means outlet thereby to restrict a signalfrom said first valve means outlet to said control inlet of said secondvalve means, thereby to open said flow path from said second valve meansinlet to said second valve means outlet, and said second valve meansinlet being also connected to said fluid motor means and providing anexhaust to said motor means when said fluid flow path through saidsecond valve means inlet and outlet to the atmosphere is open, saidchamber inlet also being connected to said inlet of said second valvemeans through restrictor means thereby to exhaust said chambersimultaneously with the exhaustion of said motor means such that uponexhaustion of said chamber, said first valve means opens and said secondvalve means closes thereby to provide said motor with fluid until saidaccumulator chamber again accumulates fluid causing the system tooscillate.
 8. The combination of claim 7 wherein said restrictor meansis variable.
 9. The combination of claim 7 wherein said combinationincludes second restrictor means at said inlet to said first valve meansand third restrictor means at said outlet of said first valve means tothe atmosphere.
 10. The combination of claim 7 wherein said motor meansincludes a piston responsive to fluid flow output from said oscillatormeans, said piston operative to drive a piston rod which in turnoperates means to change said measurable parameter to a substantiallypreselected value sensed by said sensing means.
 11. The combination ofclaim 7 including restrictor means in said supply to said oscillatormeans.
 12. The combination of claim 7 wherein said motor means operatesmeans to alter said measured parameter so that said logically responsiveoutput of said fluid pressure sensing means is terminated.